Method to due cotton and other substrates with a micro-organism biomass containing indigo

Abstract

A biomass containing biologically produced indigo or a derivative thereof which is used for dyeing without isolating the indigo dye from the rest of the solid biomass before dyeing. Cotton dyeings of clean pure shade can be obtained by a vat dyeing procedure which have the usual fastness properties associated with the active substance.

What is claimed is: 
     
       1. A method for dyeing a substrate comprising applying to the substrate a biomass containing indigo or a derivative thereof in which the dye has been produced by a microorganism without isolating the dye from the rest of the solid biomass before dyeing. 
     
     
       2. A method according to claim 1 comprising producing indigo or a derivative thereof by a microorganism to form a biomass;   lysing the cells of the biomass; and   dyeing the substrate with the solid biomass without isolating the indigo or its derivative from the rest of the solid biomass.   
     
     
       3. A method according to claim 2 comprising drying a solid biomass containing indigo or a derivative thereof prior to dyeing. 
     
     
       4. A method according to claim 3 in which the biomass is dried by a sprayer to form a powder or in a fluidised bed to form granules. 
     
     
       5. A method according to claim 3 in which the biomass is homogenised after producing indigo or a derivative thereof but prior to drying. 
     
     
       6. A method according to claim 1 in which the substrate is a hyroxy group- or nitrogen-containing organic substrate. 
     
     
       7. A method according to claim 6 in which the substrate is cotton. 
     
     
       8. A method according to claim 1 whereby the dyeing method is a vat dyeing method. 
     
     
       9. A substrate dyed by a method according to claim 1.